Evaluation Of Cool-Season Turfgrass Species Mixtures For Roadsides.

An essential component of successful road construction is the establishment of functional and sustainable roadside vegetation. The use of multi-species assemblages is known to improve overall performance of plant communities; a concept that has been shown to extend to turfgrasses. The objectives of this research were to: 1) assess roadside survival ability of turfgrass mixtures containing salt-tolerant cultivars, 2) evaluate the effect of individual species on the performance of each mixture, and 3) identify spatial trends in survival of roadside plantings. In fall 2011, three replications of 51 cool-season turfgrass mixtures were established on two roadsides: Hwy 14 near Centerville, MN, and Larpenteur Ave. in Falcon Heights, MN. Plots were evaluated for green ground cover using digital image analysis during both spring and summer 2012, and again using a grid-intersect method during spring 2013. Top-performing mixtures during spring 2012, following recovery from the winter salt applications, all contained 40% slender creeping red fescue (Festuca rubra ssp. litoralis) and maintained a maximum of 61.5% green ground cover. The summer evaluation showed that mixtures with tall fescue performed the best, likely due to high temperatures during that summer. Mixtures exhibiting the greatest level of turfgrass cover in spring 2013 contained significant proportions of slender creeping red fescue, some Kentucky bluegrass (Poa pratensis L.), and hard fescue [Festuca trachyphylla (Hack.) Krajina], and maintained a maximum of 45.8% green ground cover. Grid-intersect data from spring 2013 showed a significant and site-dependent effect of distance from the road on the probability of retaining living turfgrass cover, which ranged from 0 to 0.92. Data indicate that seed mixtures containing fine fescues along with small proportions of tall fescue have the best chance for survival on roadsides and the effect of proximity to the road is site dependent indicating potential topographical effects on survival.